1. Technical Field
The present invention pertains to fluid flow measurement. More particularly, it pertains to apparatus and methods for gauging the flow of liquid in an open channel.
2. Description of the Prior Art
The need for systems and methods to measure open channel liquid flow has existed for a long time. The volumetric flows of aqueducts, canals, and viaducts must be closely monitored. Pipelines transporting sewage often are maintained in an open channel state, the amount of effluent failing to fill the cross section of the sewage pipe.
The determination of a flow rate in an open channel requires knowledge of both the velocity and depth of the flowing liquid. Mathematical computations may then be performed upon the velocity and depth data to derive the volumetric flow rate.
The acquisition of the necessary variables has produced a substantial volume of technology. Liquid depth gauges of the air bubble type are disclosed in U.S. Pat. No. 3,638,490 of Buettnes, No. 3,475,959 of Glassey and No. 3,587,316 of Kapteyn. Flow measuring devices using electromagnetic probes are disclosed in U.S. Pats. to Marsh No. 3,885,433, Darby No. 3,898,881, Sturgeon No. 2,949,551, Rolf et al No. 3,757,576 and Banks No. 3,802,262. United States patent No. 4,083,243, issued Apr. 11, 1978 to Lawrence B. Marsh discloses a system that includes means for recording true volume flow without the necessity of empirical equations.